Clarifying an earlier story posted on CNBC, a spokesman for the base said that in a proactive measure to offset future potential problems, crews decided to repaint some fuel trucks with white reflective paint to deflect heat and keep the fuel cooler inside.

"Every jet has a threshold," said Major Matt Hasson of Luke AFB public affairs, though no one can provide CNBC with an exact temperature for the F-35.

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So far, however, "The jets are performing phenomenally...there's no problem."

"This is not an F-35 issue; there are no special restrictions on the F-35 related to fuel temperature. The F-35 uses the same fuel as other military aircraft. It can fly under the same temperature conditions as any other advanced military aircraft," the Pentagon's F-35 Joint Program Office told CNBC.

So why repaint the trucks? Maj. Hasson said the base wants to get ahead of any potential issues as its fleet of F-35s expands from a handful to a total of 144.

Luke AFB is one of seven bases testing the F-35 and beginning pilot training. Fuel trucks at Luke sit near runways and do not have any shade from the sun. Repainting trucks for $3,900 each is a relatively cheap solution.

So far, only one truck has been repainted. Whether the new paint solves the problem is still being determined. The idea has also been tested at Edwards Air Force Base in Southern California, another area where the heat hits triple digits, but Maj. Hasson said Edwards was doing a general test of the concept. It was not related to the F-35 specifically.

The new paint job at Luke "ensures the F-35 is able to meet its sortie requirements," Chief Master Sgt. Ralph Resch, fuels manager at the 56th Logistics Readiness Squadron, said in an item posted on the Air Force website. "We are taking proactive measures to mitigate any possible aircraft shutdowns due to high fuel temperatures in the future."

Maj. Hasson said "aircraft shutdowns" does not mean engine shutdowns, but a shutdown in general operations due to high fuel temperatures.

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There have been no publicly reported cases of current jet fighters experiencing problems with hot fuel. At the same time, repainting trucks bright white could make them easier targets if based in hostile territory subject to high temperatures, such as deserts. Temperatures in Iraq, for instance, can exceed 120 degrees.

"The long-term fix is to have parking shades for the refuelers," Resch said. The Air Force is also testing the idea of maintaining fuel trucks' traditional green color and instead covering them with a heat-reflective coating.

Lockheed Martin last month signed a $4.7 billion deal for 29 more of the aircraft for the United States and five close allies. It's anticipated that eventually 200 of the aircraft will be in operation in eight countries.

Editor's note: An earlier version of this story cited Air Force sources who indicated that the F-35 can't tolerate fuel that exceeds a certain temperature. The Air Force base public affairs office implied to CNBC at that time that crews testing the state-of-the-art jet fighter discovered the problem and were trying to solve it. The Air Force subsequently said that its efforts, which include repainting fuel vehicles, were meant to be proactive in case of future problems rather than designed to fix existing issues.